Without limiting the scope of the invention, its background is described in connection with film-type supercapacitors. Lithium thin-film batteries have been developed but when compared to general lithium batteries their charging performance per volume is worse and their production costs are much more costly. As a result, it is difficult to apply them to bio-application fields such as artificial organs, prosthesis and micro-robots.
A supercapacitor may be used as an energy storage means and may replace the lithium batteries as a next-generation energy storage device that can be quickly charged and discharged within several seconds, provides 10 times higher power than rechargeable batteries, and provides a semi-permanent lifetime over 500,000 cycles. The energy storage level per volume is more important for a very small electronic device that is light in weight so the film-type micro-supercapacitor as a power supply means that it is very appropriate for the very small electronic device. The energy storage of the supercapacitor per weight is substantially equivalent to 1/10 that of conventional batteries and the energy storage level thereof per volume is similar to that of the lithium batteries, and recent reports say that the supercapacitor outperforms the existing batteries regarding energy density and power density per volume.
In addition, film-type micro-supercapacitors do not use rare earth metals so it is inexpensive and environmentally friendly. Film-type micro-supercapacitors do not generate oxidation-reduction reaction that may result in explosive characteristics.
U.S. Pat. No. 8,951,306, entitled, “Film-type supercapacitor and manufacturing method thereof” discloses a film-type micro-supercapacitor and a manufacturing method thereof including a method for manufacturing an electrode film by using graphene or graphene oxide, a method for forming a two-dimensional electrode by separating a graphene or graphene oxide electrode film into two independent electrodes through patterning, a method for forming an in-plane structure of the two-dimensional electrode, a method for forming a current collector on an electrode, and a method for manufacturing a supercapacitor with a micrometer thickness by supplying an electrolyte to the two-dimensional electrode.
U.S. Patent Application Publication No. 2013/0217289, entitled, “Super capacitor thread, materials and fabrication method” teaches a one-dimensional super capacitor thread with a thin conductive wire electrode. An active layer of silicon nanoparticles and polyaniline surrounds the electrode. An electrolyte layer surrounds the active layer. The electrolyte layer can be a layer of polyvinyl alcohol (PVA). A super capacitor can be formed with two or more of the threads, such as in a twisted pair configuration. The dimensions of the super capacitor can approximate standard threads used in clothing, for example.
U.S. Pat. No. 9,048,029, entitled, “Flexible conducting polymer energy storage device” discloses an electrochemical redox supercapacitor. The supercapacitor includes two thin films of electrically conducting polymer separated by an ion-permeable membrane and including an electrolyte disposed between the two thin films. Electrical contacts are disposed on outer surfaces of the two thin films. The supercapacitor is flexible and may be rolled, folded on itself, or kept substantially flat. The entire contents of which are incorporated herein by reference.